V.34

V.34 is also referred to as V.fast and transmits duplex at 28,800 bps. V.fast uses multi- frequency quadrature amplitude modulation with channel separation by echo cancellation.

With adaptive matching, dynamic control and intelligent frequency selection, V.34 ensures optimum data transmission and thus good data throughput even under difficult transmission conditions. Thus, with V.34, transmission rates between 2,400 bit/s and 21,600 bit/s can be achieved at a step rate of 2,400 baud. At 3,000 baud, transmission rates range from 4,800 bit/s to 26,400 bit/s, and at 3,200 baud, transmission rates range from 4,800 bit/s to 28,800 bit/s. The V.34 standard was adopted in 1994. The maximum transmission rate is 33.6 kbit/s.

Other features of V.34 include the V.8 negotiation handshake to speed up connection establishment, line probing to suppress line interference, nonlinear coding for optimum receive-side decoding, pre-coding and pre- emphasis to boost frequency ranges, shell mapping to distribute signal points evenly in the so-called phase star, rate negotiation to adapt the transmission rate to the transmission conditions, and the Adaptive Power Control( APC) function to adjust the signal level.